Absolute calibration of size exclusion chromatography for coal derivatives through MALDI-ms

This paper reports the fractionation and subsequent examination of two, very different coal derived materials, a coal tar pitch and a commercial liquefaction extract. These were separated on the basis of their retention in a typical preparative size exclusion chromatography apparatus using THF as the eluent. Matrix assisted laser desorption mass spectrometry, using the small molecules of the sample as matrix, has been used to examine the various fractions from preparative s.e.c. and the peak mass intensities have been used to define an absolute calibration of the s.e.c. separation. Limitations of the methods are discussed. The u.v.-fluorescence spectra of the fractions were recorded and trends in the spectra are described. The fractions were also analyzed by size exclusion chromatography employing N-methyl-2-pyrrolidinone as the chromatographic eluent. The main advantages of this system over traditional solvents is the avoidance of surface adsorption effects observed with THF and the more complete solution of coal-derived material. (C) 1998 Elsevier Science Ltd. Ail rights reserved.